Classification of cultivated rices into indica and japonica types by the isozyme,RFLP and two milled-rice methods

Four methods for classifying cultivated rices (Oryza sativa L.) (including IR varieties) into indica and japonica types — waxy gene product in endosperm starch, glutelin ₃ molecular weight in milled rice, RFLP polymorphism at the Wx locus and Glaszmann's isozyme method — were compared. On the basis of the two endosperm traits and the RFLP method Glaszmann's group 1 (indica) was classified as mainly indica and intermediate groups 2, 3 and 4 as exclusively indica. However, the endosperm traits classified Glaszmann's group 5 as mainly indica, while the RFLP method classified it as japonica. The RFLP waxy gene probe was closest to the isozyme method in classifying group 6 as japonicas; the waxy gene product gave mainly indica reaction even in group 6, and the glutelin ₃ method was intermediate. All IR rices were classified as being indica on the basis of Wx gene product and by Glaszmann's method, but a few were classified as japonica by the glutelin ₃ method and by the RFLP waxy gene probe.